In the industrial revolution, early power units were steam engines. Steam engines typically then used a cylinder and a piston confined to axial movement with a rod connected to a wrist pin which allowed the power rod to impart rotational movement to a shaft or axle. This basic structure can be recalled most notably in steam locomotive engines. As engines grew in complexity, multiple cylinders in the same engines delivered their respective power strokes to a rotating crankshaft. At the end of the rotating crankshaft, sprockets or gears were affixed that further imparted rotational energy to other units by means of drive shafts, chains, or belts. The driven units receiving this reciprocating motion typically included gear reduction units, hydraulic pumps, and additional crankshafts. These various connections and parts resulted in (1) inefficiency, (2) complexity, (3) additional maintenance, and (4) increased weight. Every bearing in every connection results in loss of efficiency. For instance, chain drives from sprockets are considered very efficient with an efficiency of approximately 95%. Drive shafts operating through gears have an efficiency in the range of 80% to 85%. The typical losses of efficiency are multiplied at every connection, every sprocket, every separate chain, and every gear. As the connections increase, the loss in efficiency and power can be substantial. This loss in efficiency is power that is dissipated and not available as useful energy. Secondly, the additional parts result in complexities of design and increased maintenance. Every bearing, sprocket, chain, etc. requires lubrication, periodic service or replacement and movement coordination with the various parts. This in turn results in increased cost. Additionally, the complexities and extra parts add extra weight. These considerations result in further increased inefficiencies and places a limiting factor upon applications where weight is a significant consideration, such as light power units used in aircraft, automobiles, and portable installations.
Regarding references in the art, the patent of Brown, U.S. Pat. No. 27,426, is a very old steam pump mechanism defining a double acting piston. Understanding of the Brown mechanism, it operates with a straight rod which in turn connects with an articulated joint which in turn connects with a heart piece at mid portions. The linear stroke is converted into rotary motion by the frame along an eccentric rod. The construction is unsuitable for high speed operation.
Another patent is Frisbie, U.S. Pat. No. 766,237, which shows a similar construction to the Brown patent. It contains a direct linkage from the pump cylinder to the valve chest for controlling the supply of steam. Since the direct linkage axially moves left and right, an attached linkage turns a crank connected to a fly wheel. It solely depends upon steam power, which is less responsive in part because the steam cylinder depends upon another power source to produce the steam to move the piston. Axial movement of the piston is inherent and typical of steam cylinder movement. Rotational movement of a steam powered crankshaft is a virtue in Frisbie, but it is a drawback for modern combustion engines and is avoided by the present invention. This attribute of the present invention enables improved efficiency and weight reduction.
The patent of Eickemeyer, U.S. Pat. No. 138,622, is similar to the Frisbie in major aspects. It also contains a direct linkage from the power source to the pump with an attachment, has axial movement, and imparts rotational movement to a fly wheel.
The Mallary patent, U.S. Pat. No. 2,674,401, shows an internal combustion engine with a compressor. However, it does not use direct acting linkage, but instead it depends on a power rod rotating about a crankshaft which imparts rotational movement to a timing mechanism and causes the pump rod to move in a radial or rocking motion. One disadvantage of the Mallary mechanism compared to the present invention is that the forces from the power stroke and return stroke cause unnecessary and excessive forces acting on the crankshaft. These forces have to be counteracted by heavier bearings, increased maintenance on the bearing with increased lubrication, and stronger materials to carry the torsional forces. The present invention eliminates rotational or rocking motion of the main power rod. The main power rod movement is directly linked between the power piston and the pump piston. Therefore, higher stresses from combined torsion and compressive or tensile stresses are eliminated. This allows lighter weight or even composite material construction of the main power rod. The rotational movement of selected components of the present invention is simply to perform ancillary functions, i.e., timing and coordination of the various assemblies, restriction of the stroke, and provide a convenient input from a starter, or to drive an oil pump, if necessary. However, the main forces are coupled primarily through the axial movement of the power rod without rotation. Indeed, the power rod can be fixedly coupled at both ends without bearings or wrist pin.